Generally, in a mobile communications system, a function unit for calculating a location of a terminal is provided at a mobile communications network, and a location service is provided such that a location of a terminal is sent to an entity periodically or according to a request.
A network structure relating to the location service depends on an inner network structure such as 3GPP or 3GPP2. There are many techniques for calculating a current location of a terminal, for example, a cell-ID technique to send an ID of a cell to which the terminal belongs, another technique to measure time when electric wave is sent to each base station adjacent to the terminal and then to calculate a location of the terminal by using a triangulation, a Global Positioning System (GPS) technique, and the like.
In order to provide the location service to a user, a lot of signals and location information have to be sent between a terminal and a location server. Accordingly, positioning technologies for providing a location service, i.e., a location service based on a location of a mobile terminal is being widely spread. These techniques may be provided by a user plane, and a control plane. A technique to provide a location service through the user plane is referred to as Secure User Plane Location (SUPL). The SUPL is an effective method to send, to a network, location information required to calculate a location of a mobile station, and serves to send location assistance information such as GPS assistance. Also, in the SUPL method, a user plane data bearer is used so as to transfer position technology related protocols between a mobile terminal and a network.
Generally, an SUPL network relating to a location service in a location information system includes an SUPL Agent, an SUPL Location Platform (SLP), and SUPL Enabled Terminal (SET), and so on. The SUPL Agent is a logic access point for using substantially measured location information, and the SLP is an access point of a network that accesses network resources so as to obtain location information. And, the SET is a terminal that can communicate with an SUPL network using an SUPL interface, and interworks with the SUPL network through a user plane bearer thereby to support procedures defined by the SLP. Here, the SET may be implemented as one of User Terminal (UE) of UMTS, Mobile Station (MS) of GSM, a Laptop Computer having a SET function therein, and Personal Digital Assistants (PDA). Also, the SET may be implemented as various mobile terminals connected to a network through Wideband LAN (WLAN).
In a location information service, a network registered by a user is referred to as a ‘Home Network’, and a network corresponding to a region to which the user moved is referred to as a ‘Visited Network’. Accordingly, an SLP inside the Home Network is referred to as an ‘Home-SLP(H-SLP), and an SLP inside the visited network is referred to as a ‘Visited-SLP(V-SLP).
When an SUPL procedure is started in a network of the location information system, an SLP to which an external client firstly accesses is referred to as ‘a Requesting-SLP(R-SLP)’. The R-SLP serving as a logic entity may be or may not be identical with an H-SLP. And, a SET situated in a location to be targeted is referred to as a Target SET.
The SLP serves as a network element and includes an SUPL Positioning Center (SPC) to substantially calculate a location of a terminal, and an SUPL Location Center (SLC) to execute other functions rather than the calculation of location information. Here, the SLC executes roaming, resource management, and so on.
The location information system may be implemented in a proxy mode in which a SET communicates with an SPC through the SLC for calculating location information of the SET, and in a non-proxy mode in which a SET is directly connected to the SPC for calculating location information of the SET.
A triggered location service in an SUPL indicates providing location information of a target SET whenever a specific condition occurs. The triggered location service includes a Periodic Triggered service for periodically providing location information of the target SET, and an Area Event triggered service for providing location information of the target SET whenever a specific event occurs.
In the conventional triggered location service, once a triggered session is initiated, the triggered session is continuously performed unless an area event occurs, or a service duration time is expired, or the triggered session is forcibly ended. That is, once a triggered session is initiated, the triggered session is continuously performed for a long time.
However, as the target SET is under a specific circumstance, it may be difficult for the target SET to maintain the triggered session currently being executed. Also, a user may want pause of the triggered session for his or her privacy protection. In this case, the triggered session being currently performed is unintentionally ended, although a requester for the triggered location service doesn't desire it. Here, the service requester has to again request a triggered location service from a network (network that performs a triggered location service). This causes inconvenience to a service requester (user), and causes consumption of resources of a network.
In order to solve these problems, has been proposed a method for pausing an initiated triggered session, which will be explained in more detail with reference to FIG. 1.
FIG. 1 is an exemplary view showing a session pause procedure in a triggered location service in accordance with the conventional art.
Referring to FIG. 1, a target SET 30 sends a pause request message for pausing a triggered session being currently performed, which will be explained in more detail.
Firstly, a triggered location service is being currently performed (S11). An SUPL Agent 10 is receiving location information of the target SET 30. Here, the SUPL Agent 10 is an entity mounted to a terminal (source terminal) and executing an SUPL-related function.
When the target SET 30 wants to pause the triggered session being currently performed, the target SET 30 sends a pause request message to an H-SLP 20 (S12). The H-SLP 20 is an SUPL server of a Home Network to which the SUPL Agent 10 is connected.
Then, the H-SLP 20 informs the pause request to the SUPL Agent 10, and receives a response about the pause request (S13).
That is, the target SET 30 may pause the triggered session being currently performed through the conventional session pause procedure.
However, the conventional session pause procedure has the following problems.
For instance, when establishing a triggered session, a condition may be added to the triggered session. Due to the added condition, the triggered session may not be started again.
More concretely, in the case that the added condition corresponds to a time condition, when time for the triggered session is over (S14), the H-SLP 20 determines that the triggered session has ended, thereby deleting all Information relating the triggered session (S15).
However, since the target SET 30 does not notice the ending of the triggered session, the target SET 30 requests the triggered session again (S16). This causes an error occurrence (S17).
Furthermore, since the target SET 30 does not notice the ending of the triggered session, the target SET 30 unnecessarily continues to maintain information about the triggered session. This causes resources waste.